In some situations, a customer of an electronic system may be able to upgrade the electronic system by adding a circuit board. The additional circuit board may add functionality, or increase the processing power or bandwidth of the electronic system. In one conventional situation, an electronic system includes multiple circuit board modules which connect to a backplane or midplane through a card cage that holds the circuit board modules in a side-by-side manner. Each circuit board module includes (i) a main circuit board, (ii) a daughter card which mounts to one side of the main circuit board, and (iii) a metallic tray which mounts to the opposite side of the main circuit board for EMI shielding purposes.
When a customer is ready to upgrade a circuit board module of the electronic system, the manufacturer ships a supplemental card to the customer. The customer then disconnects the daughter card from the main circuit board, attaches the supplemental card to the main circuit board and then reattaches the daughter card to the main circuit board with the daughter card and the supplemental card connecting to the same side of the main circuit board. As a result, the upgraded circuit board module now includes the main circuit board, the daughter card and the new supplemental card. The distance between the supplemental card and the main circuit board is smaller than the distance between daughter card and the main circuit board.
It should be understood that, in the upgraded situation, the supplemental card is in an advantageous location relative to the main circuit board due to physical constraints of the electronic system; In particular, in its current location, the supplemental card properly fits relative to both the main circuit board and the daughter card while enabling satisfactory cooling of the components of all three boards. Additionally, the supplement card is unable to mount to the other side of the main circuit board (i.e., the side opposite the daughter card) due to the presence of the metallic tray on that other side. Furthermore, the supplemental card is unable to mount to above the daughter card (i.e., on the same side of the main circuit board as the daughter card but further away from the main circuit board than the daughter card) due to space limitations between neighboring circuit board modules within the card cage.